Impact pulverizer



Sept. 30, 1952 CROFT 2,612,320

IMPACT PULVERIZER Filed Jan. 5, 1949 6 Sheets-Sheet l INVENTOR Sept. 30, 1952 G CROFT 2,612,320

IMPACT PULVERIZER Filed Jan. 5, 1949 6 Sheets-Sheet 2 INVENTOR Sept. 30, 1952 CROFT 2,612,320

IMPACT PULVERIZER Filed Jan. 5, 1949 6 Sheets-Sheet Z5 INVENTOR .i George M- CFO/ fig W Sept. 30, 1952 v CROFT 2,612,320

IMPACT PULVERIZER Filed Jan. 5, 1949 6 Sheets-Sheet 4 fig. 7.

INVENTOR GeorgeMCro/Z a; h 6011.441? aa Sept. 30, 1952 chop- 2,612,320

IMPACT PULVERIZER Filed Jan. 5', 1949 6 Sheets-Sheet s INVENTOR George M. Cro/z 4 h m Emu: WM

aciasco I,

29. These bosses and plate 28 are drilled and tapped for threaded engagement with the rear of a nozzle 3|! to which a gaseous fluid such as ure 3 and is held against rearward movement A barrel 32 is fitted into each sleeve 25 in the inner end thereof as illustrated in Figby a strip 33 abutting the inside of cover plate 29. The forward or inner end of each barrel 32 projects through the inner end of sleeve 25 and througha registering opening 34 in inner wall 2|]. The grinding jets, which also recirculate, of this mill comprise the nozzles 3|] with f their associated barrels 32 respectively. Each grinding jet has an annular inlet 35 which with the space adjacent recess 26 in sleeve 25 constitutes the inspiration zone therefor. These four grinding jets have a common point of intersection on the vertical axis of the mill as may be seen in Figure 6.

' A feed jet casing 33 projects into chamber 2| through plate 22. Casing 35 is downwardly'inclined and is directed substantially in the direction of said common point of intersection and so as to clearthe projecting inner ends of the adjacent barrels 32. Like barrels 32, the lower end of casing 36 is reduced in diameter to form a reduced V enturi-like throat 31 therethrough lined with a suitable temperature and wear-resistant material 38. A nozzle 39 extends downwardly f and centrally inside "casing 33 having a flange to which a cover plate 40 is bolted as illustrated in Figure.v 1. Longitudinal, radially extending vanes 36a center the jet end of nozzle 39 inside casing 36 where it is held by a set screw collar attached to plate 40. A pipe connection 4| sup plies superheated steam or compressed air to nozzle 39 through a pipe union 4|a. A feed inlet zone 42 behind throat 37 is the inspiration'zone for the feed jet comprising nozzle 39 and the barrel defined by casing 35 and material 38. An

air-intake pipe 43, which normally'is left open,

Q is connectedat an angle, as shown in Figure 2, to casing 36 and admits air adjacent feed inlet zone 42. The air which enters intake pipe 43 chamber.

4 confined by the relatively volume of the Outlets from the chamberare provided by recirculating passages 54, of which there .are two .in number in the embodiment shown.

These passages defined by the respective ducts '55. extend radially away from impact chamber 2|, Intermediate walls 29 and I7, passages 54 and ducts 55 fork or divide and connect the grinding jets on each side thereof respectively.

Ducts 55 are divided horizontally for assembly and are assembled by bolting through the registering flanges 56. The outer ends of ducts 55 terminate in collars 51 which surround andclose the respective recesses'23 so that impact chamber 2|-is directly connected to the inspiration zones 35 which constitute terminals for the" forked divisions of the 'passag'e's 54. Passages 54 are soproportioned that the radial portions'thereof leading from chamber 2|"aresubstantially'of twice the cross sectional area as compared with the cross sectional area of either curvilinear branch thereof continuing into inspiration zone- 35. In this way, a relatively high velocity'of streams of gaseous fluid and suspended material is maintained in a uniform manner, keeping impact chamber 2| substantially free of any tendency to collect any solid material therein.

Four uptake pipes 58 suitably sectioned as shown-in Figure 3 for assembling'ease'connect inspiration zones 35 throughregistering openings in collars 5'1 and plate l9 with a corresponding number of tangential'inlet openings 59 fastened to the underside of top plate l3 in an annular arrangement. The cross sectional area of each uptake pipe 58 is usually somewhat larger than the cross sectional area of thebranch of duct 55 connected to the corresponding inspiration zone 35. Hence, the velocities in passages 54 are sufiiciently greater than the velocities'in uptake is clean having been filtered by passing through" air filter l5. A horizontal screw conveyor conduit 44 opens into casing'36 at inlet zone 42 and is welded to casing 36.

Conduit 44 extends outwardly through a corresponding opening in casing l0 and terminates in a bearing cover plate 42 bolted to the outer flange 46 of conduit 44. As shown, conduit 44'is made up in sections for the ready disassembling thereof in case reipairs or replacements are needed; Conduit 44 is supported at its inner end in a saddle block 4| affixed to plate 19. A saddle pedestal 43 supports the outer end of conduit 44. A flared hopper 49 opens into the top of the outer end of conduit 44 and coarse particles of coal or the i like to beground are fed into hopper 49. These particles are conveyed to feed inlet zone42 by a screw conveyor 50 which fits tightly in con- ;duit .44. The shaft 5| of screw conveyor 53 is ijournaled in cover plate 45 and terminates at pipes 58 to cause material tobe ground which is coarser than pulverulent material ofan adjustably selected particle size to pass into the inlets 35 of the grindingjets for recirculation and regrinding. This recirculation and regrinding is in addition to any grinding'resultin'g from'the projection through the fee'd'jet of the material into impact chamber'2l and possibly against wear plate 23 Material not exceeding that selected particle size can be called pulverulent material and will rise under the prescribed conditionsfset for the mill in; the construction and operation thereof, in uptake pipes 58, being suspended in V the gaseous fluid constantly rising in those pipes as a consequence of the new gaseous fluid'constantly being. fed into the mill by the'respective jets. 1

A classifier 69 has an outer casing 3| substantially in the form of an inverted cone, which casing is suspended in a central manner within casing Hi from top plate I3. A vertical riser pipe 62 extends downwardly into classifier 3|! for a portion of its vertical length and projects upwardly through plate |3 whence it is bolted to an its outer end in a beveled gear 52 which meshes c-phere in impact chamber 2|. The gaseous fluids Land-solid particlesinthat chamber are closely outlet pipe 63. A bell-type shield 64 is suspended by brackets 55 from the lower endof riser |52. A return leg 33 is connected to the lower open end of classifier 60 and leads into a downwardly inclined nozzle casing 67 which. projects into impact chamber 2| through plate 22. Nozzle casingfil includes a suction jet assemblywhich is substantially directed towardsaid .common point of intersection inchamber. 2|. A Venturilike throat 68 is provided, at the lower .endof casing 61 by-suitable temperature andwear-re sisting material 69 whichflconstitutes the barrel :than-theaggregate cross sectional area oisaid ducts,.a common classifier into which said uptake p ipes.empty, means for effecting rotation ofsaid .streams'passing-into said classifier, a riser in said .;,cla ssifier for said pulverulent -material not exceeding a predetermined particle size, a return leg i 1 i said;; classifier gfor rejected pulverulent e2;-

ceeding such a predetermined particle size, said ireturmleg emptying into said suction zone, and .-means I01 forcing gaseous fluid through said jets create an inspirating effect respectivelyin said zones, V 1 a ..=2 In animpactpulverizer using gaseous fluid for pulyerizing coal particlesor the like, a closed impact chamber, a plurality of grinding jets having; inspiration zones associated therewith, said rinding jets being directed-toward a common point of intersection in said chamber, said chamber closely;surroundingrthe space between the :deliyery ends of said grinding jets,,a plurality of recirculating ducts leadings from said chamber re spectively to said inspiration zones; a feed jet locatedvabove said grinding jets and emptying into said; chamber, said feed jethaving a feed inlet zone, means for supplying coarse coal par- .ticles or the like to bepulveriz'edto said feed inlet zone, a .suctionjetlocated above said grinding jets and emptying into said chamber, said suction ;jet having a suction zone, means for admitting a gaseous fluid to said suction zone, a plurality of uptake pipes connected to said ducts adjacent said inspiration zones, said uptake pipes being adapted to provide an outlet for continuously rising streams of pulverulent coal particles or the like suspendedin said "gaseous fluid, means con- ,nected to saiduptake pipes and adapted to separate said pulverulent coal particles or the like which exceed a' predetermined particle size, means for returning said 'pulverulent material "exceeding such predetermined particle size to jsai'd suction zone, and means for forcing gaseous fiuid'through saidjets to create an inspirating reflect'frespectively in said zones. V 3; Inan'impact pulverizer using gaseous fluid for pulverizing coal particles or the like, a closed impact chamber, 1 a plurality of grinding jets having 1 inspiration zones respectively associated therewith, said grinding-jets being directed toward 'a common point of intersection in said chamber, said chamber'closely surrounding said common'pcint of intersection, at least one duct 'for'ming 'a' restricted passage connecting said chamber'ancl'said inspiration zones, afeed jet "located above" said grinding'jets and emptying into-said chamber, said feed jet being adapted to deliver coarse coal particles or the like to be pulverized into said} chamber, at least one restricted outlet pipe for pulverulent coal particles or the like'suspended in said gaseous fluid, said restricted outletpipe being connected to said re-- 'st'ricted passage, separating means connected to sai'd restricted outlet for rejecting said pulverulent coal particles or thelike which exceed a predetermined particle size; and means connected to separating -means' for returning saidir'e-u .saidchamberv lam-sac 8 i t fll'v'ru t; a ca casses t l k 9 4. ,Inan impact pulverizer gaseous for pulverizing coal particlesv or the like,- .a. con- .fined chamber formingljan irnpact zone, a-|plurality of grinding jets directed toward a common intersection in said zone said grinding jets having respective inspiration zones outsidesaid c am .v a lea n t f rm n restricte passage means connecting said; impact zone and saidinspiration zoneaat least ene pipe forming restricted outlet means substantially forming a branch of said restricted passage means, said restricted outlet means being adapted tocarry oil pulverulent material suspended in said gaseous fluid, feed means located abovesaid grinding jets and adapted to delivercoarse coalparticles or the like to be pulverized to said impacfizone,

and separating means connected tosaid restricted outlet means for rejecting such of said pulverulent material which exceeds a predetermined particle size.

5. In an impact pulyerizer for coal particles or the like using gaseous fluid, a closed impact chamber adjacent the bottom of said pulverizer, a plurality of substantially-horizontal grinding jets having inspiration zones associated therewith, said grinding jets being directed toward a common point of intersection in said chamber, said chamber closely surroundingthe space between the, delivery ends ofp said grinding. lets, a plurality of substantially horizontal recirculating ducts leading from. said chamber respectively to said inspiration zones, said inspiration zones comprising the respective terminals for said ducts,

a feed jet in the plane of said grinding jets, said feed jet emptying into said chamber and directed toward said common point, said feed jet having a feed inlet zone, ascrew conveyor adapted to supply coalparticles or the like tosaid feed inlet zone,-; a downwardly directedsuction jet above said grindingjets, said suction jet emptying into-said chamber and directed toward said common point'said suction-jethavinea suction zone, a plurality of uptake pipes connected to said ducts adjacent said inspiration zones,

. said uptake pipes being adapted to .provide'an outlet for continuous streams of pulverulent coal particles or the like suspended in said, g seous fluid, said uptake pipes further being somewhat larger in aggregate cross sectional area than the aggregate cross sectional; areagofsaidducts, a common la ifi nto h ch, sai ake i empty, means for efiecting i-rotation of "said streams passing into said classifier, a riserinv said classifier for said pulverulent material hot exceeding a predetermined particle size," a return leg in said classifierforqrejected pulverulent exceeding such a predetermined particle size. said return; leg emptying into said suction zone, and

means for ,forcing gaseous fluid th jOll h said jets to create an inspirating efiect respectively in said zones.

6. In an impactpulverizer using, gaseous fluid for lpulverizingcoal particlespr the like, aclosed impact chamber -a plurality of grinding jets having inspiration zones associated therewith, said grindin jets being directedtoward a common point of intersection in said chamber, saidchamberclosely surrounding the space between the delivery ends of said'grinding jets, a plurality of recirculating ductsjleading from said ,chamber spe tivelmo; aid ins irat azon a eedi t located substantially on a level with said grindm Jet and emn ie 1mg e a ale iambern ai 9 feed jet having a feed inlet zone, means for supplying coarse coal particles or the like to be pulverized to said feed inlet zone, a suction jet located above said grinding jets and emptying into said chamber, said suction jet having a suction zone, a plurality of uptake pipes connected to said ducts adjacent said inspiration zones, said uptake pipes being adapted to provide an outlet for continuously rising streams of pulverulent co'al particles or the like suspended in said gaseous fluid, means connected to said uptake pipes and adapted to separate said pulverulent coal particles or the like which exceed a predetermined particle size, means for returning said pulverulent material exceeding such predetermined particle size to said suction zone, said means being disposed concentrically around said suction jet, and means for forcing gaseous fluid through said jets to create an inspire-ting effect respectively in said zones.

'7. In an impact pulverizer using gaseous fluid for pulverizing coal particles or the like, a confined chamber forming an impact zone, a plurality of grinding jets directed toward a common intersection in said zone, said grinding jets having respective inspiration zones outside said chamber, at least one duct forming restricted passage means connecting said impact zone and said inspiration zones, at leastone pipe forming restricted outlet means substantially forming a branch of said'restricted passage means, said restricted outlet means being adapted to carry off pulverulent materia1 suspended in said gaseous fluid, feed means located substantially on a level with said grinding jets and adapted to deliver coarse coal particles or the like to be pulverized to said impact zone, and separating means connected to said restricted outlet means for rejecting such of said pulverulent material which exceeds a predetermined particle size.

8. In an impact pulverizer using gaseous fluid for pulverizing coal particles or the like, a confined chamber forming an impact zone, a plurality of grinding jets directed toward a common intersection in said zone, said grinding jets having respective inspiration zones outside said chamber, a duct forming restricted passage means connecting said impact zone and said inspiration zones and adapted to recirculate nonpulverulent material to said grinding jets, upwardly extending restricted outlet means substantially forming a branch of said restricted passage means, said restricted outlet means being adapted to carry ofi pulverulent material suspended in said gaseous fluid, feed means adapted to deliver coarse coal particles or the like to be pulverized into said impact zone, and separating means connected to said restricted outlet means for rejecting such of said pulverulent material which exceeds a predetermined particle size.

9. In an impact pulverizer using gaseous fluid for pulverizing coal particles or the like, a closely confined chamber forming an impact zone, a plurality of grinding jets directed toward a common intersection in said zone and having respective inspiration zones outside said chamber, said inspiration zones being closely confined, ducts forming respective passage means of restricted cross sectional area connecting said impact zone and said inspiration zones and adapted to carry all material suspended in said gaseous fluid away from said zone, said inspiration zones being adapted to recirculate the non-pulverulent material therein, upwardly extending pipes forming outlet means of restricted cross sectional area substantially forming a branch of said passage means, said outlet means being adapted to carry off pulverulent material suspended in said gaseous fiuid, feed means adapted to deliver coarse coal particles or the like to be pulverized to said impact zone, separating means connected to said outlet means for rejecting such of said pulverulent material which exceeds a predetermined particle size, and adjustable means connected to said separating means and adapted to return rejected pulverulent material to said impact zone.

10. In an impact pulverizer using gaseous fluid to pulverize coal particles or the like, a closed impact chamber, a plurality of grinding jets having inspiration zones associated therewith outside said chamber, said grinding'jets being directed toward a common point of intersection in said'chamber, said chamber closely surrounding the space between the delivery ends of said grinding jets, a plurality of recirculating ducts leading from said chamber respectively to said inspiration zones, means for feeding coarse coal particles or the like to be pulverized to said grinding jets, a plurality of uptake pipes connected to said ducts adjacent said inspiration zones, said uptake pipes being adapted to provide an outlet for continuously rising streams of pulverulent coal particles or the like suspended in said gaseous fluid, means connected to said uptake pipes and adapted to separate said pulverulent coal particles or the like which exceed a predetermined particle size, and

means for returning said pulverulent material exceeding such predetermined particle size to said grinding jets.

l1. In an impact pulverizer using gaseous fluid for p'ulverizing coal particles or the like, a confined chamber forming an impact zone, a plurality of grinding jets directed toward a common intersection in said zone, said grinding jets having respective inspiration zones outside said chamber, ducts forming respective restricted passage means connecting said impact zone and said inspiration zones and adapted to recirculate non-pulverulent material to said grinding jets, upwardly extending pipes forming respective restricted outlet means substantially providing a branch of said restricted passage means, said. restricted outlet means being adapted to carry off pulverulent material suspended in said gaseous fluid, and feed means adapted to deliver coarse coal particles or the like to be pulverized to said grinding jets.

GEORGE M. CROFT.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED sTATEs PATENTS 

